Electrtic control system



Aug. 25, 1942. E. D. NUNN 2,294,343

ELECTRIC CONTROL SYSTEM Filed April 8, 1940 INV ENT OR.

lam-M ATTORNEY.

Patented Aug. 25, 1942 UNITED STATES PATENT OFFICE ELECTRIC CONTROL SYSTEM Ewing D. Nunn, Milwaukee, Wis.

Application April 8, 1940, Serial No. 328,478

7 Claims.

This invention relates to improvements in electric control systems.

One of the objects is to provide a system adapted to automatically deliver wattage of a pre-selected value for pre-selected periods at preselected intervals.

Another object is to provide an improved system for delivering high voltage 10w amperage wattage for reoccurring periods of extremely short duration.

Another object is to provide an improved sys tem for recurrently delivering wattage in accurate determined amounts and at closely controlled intervals of duplicate duration.

Another object is to provide an improved system which delivers only one charge of wattage if a failure occurs in the operation of the inter val timing means.

Another object of the invention is to provide a system wherein the component parts are so arranged and structurally related as to reduce the cost of construction and to form a compact and easily handled unit.

The foregoing objects are accomplished by combining in a system, a source of electrical power, a thermionic rectifier, a relay, a condenser, and a transformer, arranging the relay and rectifier so that the filament of the rectifier is normally connected with the source, arranging the relay and condenser so that the former is motivated and the latter charged by the establishment of space current in the rectifier, and arranging the relay and the filament and the transformer so that upon motivation of the relay th filament is disconnected from the source and the transformer connected with the condenser. The timing of the operation of the relay may be varied by change in the amount of power applied to the filament, by change in the characteristics of the relay coil, by the insertion of resistance varying the amount of current to the relay coil, or by chang of tension in the normal biasing spring of the relay. The regulation of the output wattage is obtained by varying the source of power, the capacity of the condenser, or the characteristics of the transformer. The system can deliver only one charge from the condenser if there is a failure in operation of the relay as the condenser is either connected with the source and disconnected from the transformer, or connected with The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection With the accompanying drawing, in which:

Figure 1 is a view in elevation of a unit having the parts comprising the system embodying the invention structurally arranged and related; and

Figure 2 is a wiring diagram of the electrical system embodying the invention.

Referring in greater detail to the drawing, the unit disclosed is particularly adapted for use as a fence charger. To this end the chassis of the unit comprises an elongated base B, above which is supported a deck D by supports S extending therebetween. On the deck D is positioned an L-shaped member U, the vertical leg of which is secured to the deck D to support the horizontal leg above that deck and form an upper deck. A fuse box case C, containing two fuses 2 of two ampere capacity at 250 volts, and a manually operated snap action switch 3 are positioned on the upper deck U. Two condensers 4 of approximately .5 mfd. capacity at direct current working voltage of approximately 600 volts are secured to the under side of upper deck U. On the deck D beneath the upper deck U is positioned a transformer 5 having one secondary winding adapted to step up the voltage of the source to approximately 400 volts, and another secondary winding adapted to step down the source voltage to approximately 5 volts. On deck D, adjacent the vertical leg of upper deck U, there is supported a socket for, and a type 80, thermionic, full wave rectifier tube 8. Adjacent the tube 8 there is carried in an edge clamp opening a condenser [6 having a capacity of approximately 2 mfd. at direct current working voltage of approximately 600 volts. On the under side of deck D there is supported a condenser 15 of capacity .5 mfd. at

direct current working voltage of 600 volts. Ad-

jacent thereto, is a balancing resistance l3 comprising a wire wound resistor of approximately 16,000 ohms and a carbon resistor of approximately 50,000 to 60,000 ohms. A step-up output transformer l1 adapted to develop an output voltage of approximately 7,000 volts is supported on the base B beneath the condenser l5. A terminal 2| adapted to connect the secondary winding of transformer I! to the ground is positioned beneath the transformer IT. The terminal 2|, being itself grounded to the chassis of the unit, provides a ground for the system. An incandescent bulb I9 is held at the lateral edge of Figure 1.

base B by a bracket and socket, to which is also secured a small fixed resistor I8. On the left side of base B, as viewed in Figure 1, the relay R is mounted by means of vibration absorbing rubber pedestals. The relay R is of the type generally known to those skilled in the art. It is provided with self-wiping contacts which are operated in a definite sequence by the action of the armature. The armature (when coil I4 is deenergized) is normally urged to the upward position, as shown in Figure l by spring 9, the tension of which is adjustable by screw means or other well-known means. In this position contacts I and II are closed and contact 12 is open. In order to provide snap action and prevent chattering the armature has a brass spaced button and a small, permanent, hold-out magnet. Centrally of the base is located a porcelain insulated connecting terminal 20 to which the fence wire is connected. The fence wire, as is well known, must itself be insulated from the ground.

The above parts comprising the unit charger are electrically connected, as illustrated in Figure 2, in the following manner:

To a source of electrical power I, in the form of alternating voltage of the magnitude of approximately 110 volts, as found in the customary house lighting main, is electrically connected the primary of the transformer 5. In the connection between the source and the transformer there are interposed the safety fuses 2 and the manually operated switch 3. Each lead of the primary of transformer 5 is connected to the step-uprsecondary winding 6 through one of the condensers 4. The step-up secondary winding 6 is connected to the plates of the type Bil, thermionic, full wave rectifier 8. The relay R has its contact l0 serially connected with the secondary winding 1 and the filament of the rectifier 8. This last circuit (hereinafter referred as the filament circuit) is connected serially to a balancing resistance l3, coil Id of the relay R, and the center terminal of the secondary winding 6. The filament circuit .is also serially connected with the contact H, condenser 16, and center terminal of the secondary winding 6. The condenser I5 is connected across the coil M of the relay R to smooth its action. The step-up transformer I! has its primary winding serially connected with the contact l2 and the condenser It. The secondary winding of transformer I! has connected serially across its terminals the fixed resistance l8 and incandescent lamp l'9. The secondary winding of the transformer I! is connected to the insulated terminal 20 and the ground terminal 2|.

The system has a cyclic operation as follows: ('1) Transformer 5 is energized by closing the manually operated switch 3 and voltage is induced in winding 1 causing current to flow through the filament circuit. There is simultaneously induced in the winding 6 a Voltage which is impressed on the plates of the rectifier. (2) After the elapse of a predetermined amount of time the filament reaches a temperature which will establish electronic discharge sufficient to support the flow of enough space current to energize the coil I4 of the relay R. During this time the condenser I6 is also charged. (3) After the coil I4 is sufficient- -ly energized to overcome the resistance in spring 9 and attraction of the small, permanent, holdout magnet, the armature moves to the right, as viewed in Figure 2, or downwardly, as viewed in This causes in sequence the contact II to open, the contact l2 to close, and the contact ID to open. This disconnects the condenser Hi from its charging source and connects it to the primary of the transformer II. It also disrupts the filament circuit. The condenser l6, being connected in series with the winding of the transformer I1, will discharge in an oscillatory manner, thereby momentarily inducing the stepped-up voltage in the secondary of that transformer. At the instant of the breaking of the filament circuit the filament commences to cool, immediately reducing the flow of space current. This decreases the magnetic attraction of coil I 2 until it is insufficient to offset the tension in spring 9. (4) The relay then assumes the starting position shown in Figures 1 and 2 at which time the cycle is again commenced.

It will be apparent to those skilled in the art that the interval of time consumed in the operation of the relay is directly dependent upon both the heating and the cooling of the filament in ranges of relatively high temperatures. Thus ambient temperature will in ordinary usage have no effect in altering the interval. The length of the interval can be Dre-selected by varying the tension of the spring 8, by varying the amount of the balancing resistance H3, or by changing the winding characteristics of the coil Is. The output wattage may be regulated to some extent by the period of time during which the condenser I5 is connected to the rectified current, but in this exemplification the condenser is fully charged before the relay R is motivated. The output wattage can also be regulated by varying the source of input power, the capacity of condenser 15, or the winding characteristics of transformer ll. It will thus be seen that the system is extremely flexible and can be adapted to meet varying requirements of intermittent output power.

The reason that the system is particularly adapted for the charging of electric fences rcsides in the fact that the condenser 16 can only discharge once through the winding of the transi former ll without the system going through its complete cycle, during the first step of which the transformer H is disconnected from any source of power. Hence, if there is a failure in the relay, the power output is limited to one momentary impulse and no more. Another reason why the system is particularly adapted for the charging of electric fences is that the momentary interval of power output is inherently very short, approximately of a second.

Although there are shown and described specific embodiments of the invention, many modifications thereof are possible. For example, the source of power has been shown as alternating voltage. It is, however, permissible to use a source of power which comprises unidirectional voltage. In that case it is not necessary to use a rectifying tube. Any electronic discharge tube, in which the fiow of space current is established when the filament thereof is heated to a certain temperature, may be used. In this case, the relay would (1) alternately connect the condenser to the source of unidirectional voltage and the primary winding of the output transformer, and (2) alternately connect and disconnect. the source of unidirectional voltage and the filament of the tube. The invention is, therefore, not to be restricted except in so far as is necessitated by the prior art and by the spirit of the appended claims.

I claim:

1. In combination, a source of electric power, a condenser, a transformer, means for connecting said condenser alternately with said source and said transformer, and an electronic discharge device for controlling the intermittent motivation of said means.

2. In combination, a source of alternating current, a thermionic rectifier, a condenser, a transformer and a relay, said relay being operable to connect said condenser alternately with said rectifier and said transformer, said relay being motivated by the establishment of space current in said rectifier to control the energization of the filament of said rectifier.

3. In combination, an alternating current circuit, a direct current circuit, an electronic discharge device transmitting unidirectional current to said direct current circuit and having a control filament energized from said alternating current circuit, a relay motivated by said direct current circuit, a condenser charged by said direct current circuit, and a transformer energizable by said condenser, said relay upon motivation connecting said condenser to said transformer and disconnecting said filament from said alternating current circuit.

4. In combination, a source of alternating voltage, a rectifier connected to said source for producing a unidirectional voltage and having a filament energizable by said alternating voltage, a condenser charged by said unidirectional voltage, a relay motivated by said unidirectional voltage, and a transformer energizable by said condenser, said relay upon motivation connecting said condenser to said transformer and disconnecting said filament from said alternating voltage.

5. A charger for an electric fence comprising a discharge circuit including the primary winding of fence charging transformer, a charging condenser, a charging circuit including a thermionic electronic discharge tube, and a relay for periodically and alternately placing said condenser in said charging circuit and said discharge circuit.

6. A charger for an electric fence comprising a discharge circuit including the primary winding of fence charging transformer, a charging condenser, a charging circuit including a thermionic electronic discharge tube, and a relay for periodically and alternately placing said condenser in said charging circuit and said discharge circuit, said relay being controlled by the establishment of space current in said tube.

'7. A charger for an electric fence comprising a discharge circuit including the primary winding of fence charging transformer, a charging condenser, a charging circuit including a thermionic electronic discharge tube, and means for periodically and alternately placing said condenser in said charging circuit and said discharge circuit, said means being controlled by the heating and cooling of the filament of said tube and alternately connecting and disconnecting said filament and said charging circuit.

EWING D. NUNN. 

